The present invention generally relates to a monoblock dielectric duplexer, and more particularly, to patterns of conductive electrodes on a monoblock dielectric duplexer that can accurately and simply set the capacitances of capacitors in the duplexer.
A duplexer is used in a communications device to pass transmission signals and received signals in different frequency bands. A monoblock dielectric duplexer is one of various types of duplexers widely used in the art. The monoblock dielectric duplexer comprises a block of a dielectric material. A plurality of resonant holes are made inside the dielectric block like tunnels from one surface to its opposite surface in parallel. They are at given distances from one anther in the dielectric block. The internal surface of each of the resonant holes is substantially covered with conductive materials to form a resonator. In addition, a plurality of conductive electrodes usually in the shape of a square-shape are formed on the surroundings of the openings of the plurality of the resonant holes on the front surface of the dielectric block. Each of the conductive electrodes is connected to the conductive material covering the internal surface of each of the resonant holes.
The monoblock dielectric duplexer typically comprises a transmit-filtering portion and a receive-filtering portion, wherein the frequency band of the transmit-filtering portion relatively is lower than that of the receive-filtering portion. The former consists of a first group of resonant holes, and has characteristics of passing transmitting frequencies while attenuating receiving frequencies. On the other hand, the latter consists of a second group of resonant holes, and has characteristics of passing the receiving frequencies while suppressing the transmitting frequencies. Besides, patterns of input and output terminals are disposed in the right and left ends of the front surface, respectively. An antenna terminal is disposed between the receive-filtering portion and the transmit-filtering portion.
With such a structure, the frequency characteristics related with the resonators are determined by capacitances in the dielectric block. The capacitances in turn depend upon geometries of the conductive electrodes on the front surface of the dielectric block.
Advancements in the field of mobile communication have required that the monoblock dielectric duplexer be smaller and mass-producible. However, if the physical dimension of the monoblock dielectric duplexer is reduced, the conductive electrodes formed on the duplexer must be correspondingly reduced. For smaller electrodes to provide the same capacitances, the intervals between them must be reduced. However, for manufacturing reasons, minimum intervals are required between them, so that there is a limit to reducing the intervals. Moreover, even if the capacitances are set by varying the shape or intervals of the conductive electrodes, it is difficult to design the geometries of the conductive electrodes to set desired capacitances since the capacitance between adjacent resonators and the capacitance between each of the resonators and the conductive materials of the side surfaces must be simultaneously altered. A number of modeling experiments have been required to finally provide desired capacitances in conventional monoblock duplexers, thereby increasing the production cost.
It is, therefore, a primary object of the present invention to provide an improved monoblock dielectric duplexer having such a structure that is capable of setting capacitances of the duplexer in accurate manner by finding out the relation between capacitances and the geometries of the conductive electrodes thus to improve productivity thereof.
Another object of the present invention is to provide an improve monoblock dielectric duplexer having conductive electrodes for use in precisely adjusting geometries thereof, whereby the duplexer can be small and manufactured in a simplified manner.
Still another object of the present invention is to provide an improve monoblock dielectric duplexer having conductive electrodes that adapted to set desired capacitances when the number of resonator for a transmit filter and the number of resonator for a receive filter are same, thereby to facilitate mass-product.
In accordance with one aspect of the present invention, therefore, there is provided a monoblock dielectric duplexer comprising:
a dielectric block covered with conductive material except for one side;
a first group of resonant holes bored inside the dielectric block for a transmit filter, the holes being arranged in parallel with one another;
a second group of resonant holes bored inside the dielectric block for a receive filter, the holes being arranged in parallel with one another;
a first conductive pattern, on the one side, surrounding the openings of the first group of resonant holes, and a second conductive pattern, on the one side, away from the opening of the first group of resonant holes, the first and second patterns being spaced apart and having fingers; and
a third conductive pattern formed on the side to surround the openings of the second group of resonant holes, and a fourth conductive pattern formed to the side away from the openings of the second group of resonant holes, the third and fourth patterns being spaced apart and having no fingers.
The duplexer may further comprise a transmit coupler, an antenna coupler and a receive coupler formed on the one side, wherein the transmit coupler formed adjacent to a first electrode of the first conducive pattern, the transmit coupler and the first electrode of the first conducive pattern being spaced apart and having no fingers, the receive coupler formed adjacent to a first electrode of the third pattern, the receive coupler and the first electrode of the at least one third pattern being spaced apart and having no fingers, and the antennal coupler formed between the first group of the holes and the second group of the holes.
Preferably, in the duplexer, the number of the first group of resonant holes and the number of the second group of resonant holes are the same, and the diameters of the resonant holes are identical to the intervals between the first group of resonant holes and the interval between two center holes, one each from the transmitting portion and the receiving portion, is different from the intervals. The antenna coupler may be branched with one branch closer to the transmitting portion and the other closer to the receiving portion.